Manufacture of varnishes



Patented June 13, 1944 MANUFACTURE OF VARNISHES Alfred E. Rheineck andSamuel B. Crecelius, Louisville, Ky., assignors to Devoe & ReynoldsCompany, Inc., a corporation of New York No Drawing. Application March28, 1942, Serial No. 436,626

7 Claims.

The classical method of making varnishes consisted in heating together adrying oil such as linseed oil and a varnish resin such as rosin, runcongo, damar, run copal or other natural resin ingredients. We havediscovered that very valuable varnishes can be obtained followingapproximately this old procedure, provided the drying oil ingredient issaponified' before being heated with the resin and then recombined witha polyhydric alcohol. Usually this will be done by neutralizing toremove the alkali, followed by subsequent esteriilcation. When a varnishis made in this manner, the resulting product has many excellentqualities. The viscosity increases rapidly. The water resistance of thefinal product is definitely superior to that of comparative varnishesmade from the same proportions and types of ingredients following usualprocedure. There is a definite improvement in the alkali resistance, therocker hardness is increased and these varnishes show extremely gooddrying qualities.

Thi process is particularly applicable to the drying oils havingnon-conjugated double bonds, and when we refer to drying oils, we areusing that term quite broadly to include oils averaging at leastapproximately one and one-half double bonds per acid chain, so that Weare including oils such as soybean oil which is sometimes classed as asemi-drying oil.

The oils may be saponifled with any ordinary alkali and the saponifledfatty acids may be separated from the glycerine or the glycerine mayremain in the mixture, in which case it ordinarily will be removed laterin the process so that it is available for subsequent esterification. Ifdesired, previously separated fatty acids may be used. Thesaponiflcation may be carried out with either a water or alcoholicsolution of the alkali, but ordinarily the water solution will beemployed as a matter of economy.

As regards the resin ingredient, any of the natural resins may beemployed which melt at a reasonable temperature (say between 100 C. and260 C.) and which are directly miscible wlth oil. If the high meltingpoint resins which are not easily miscible with oil are to be employed,they should first be run to lower their melting point. The resins may becombined with other ingredients as in the case of ester gum or rosinmodified phenolic resins, but ordinarily nothing is gained by using suchproducts as they tend to saponify when treated with the fatty acid oaps.However, we have found that in addition to the natural resins, we mayalso employ the synthetic varnish resins which are oilsoluble andfusible such as the oil soluble phenolic varnish resins.

Ordinarily the resin will be pre-melted and may have a small amount ofsome inert solvent such as mineral spirits, xylene, toluene or theequivalent added prior to the addition of soap. However, if an anhydroussoap made in an alcohol solution is employed, the premelting of theresin is not essential but is desirable to minimize decomposition of thesoap.

When an aqueous soap solution or wet soap is used, it is gradually addedto the melted resin with or without solvent at some temperature between100 C. and 275 C. depending upon the melting point of the resin. Thewater will be spontaneously evaporated or distilled off with thehydrocarbon solvent, which may be separated from the water and returned.When no solvent is used, open vessels can be used advantageously but inthat case the wet soap must be added gradually to the melted resin dueto the foaming which ensues.

After the soap has all been added to the melted resin the mass is heatedto a temperature of between 200 C, and 285 C., and preferably to atemperature between 240 C. and 260 C., and is maintained at the reactiontemperature for a time varying from 2 to 10 hours, depending on thetemperature employed. Within the preferred temperature range, thedesired effect ordinarily can be obtained in between 2 and 5 hours usinglinseed or soybean oil acid soaps. After the heating period, the soapand resin mixture is run into dilute mineral acids to decompose thesoap. This can be done in any way desired as is known in the art, but wefind that this step can be accomplished advantageously in using a 10%excess of sulphuric acid containing about 45% of H2804 by weight. Afterthe acidification, the mass should be washed carefully, and ordinarilythis will be done using 3 or 4 washes with hot water. If any glycerineremains in the soap the bulk of it will be removed at this time. Afterelimination of the water, the acidity of the mass is determined and theacids are esterified with a polyhydric alcohol.

The amount of resin used is determined by the oil length of the desiredfinal varnish. Thus if a 25-gallon varnish is wanted, we may use 100pounds of rosin and an amount of soap equivalent to 25 gallons of oil.This is approximately two parts of oil for one part of rosin. We havefound that our process is practically operative for various oil rangesbetween about 5 and 30 gallons. If one goes above 30-gallon oil lengththe quantity of resin present is usually insufiicient properly todisperse the soaps.

The acid value of the final fatty acid-resin mixture after washing butbefore esterification is determined and when this figure has beenobtained the amount of polyhydric alcohol required is calculated and aslight excess over the stoichiometric quantity is ordinarily employed.Various polyhydric alcohols may be employed such as glycerol,erythritol, pentaerythritol, mannitol, sorbitol and inositol or mixturesof these. Esterification is brought about by heating the mixture ofalcohol and acids by any wellknown manner as is known in the art.Ordinarily heating will be continued at temperatures between 200 C. and300 C. until the acid value reaches to which requires from 6 to 8 hours.

During the final portion of the esterification reaction, the temperatureis preferably raised somewhat, say to 280 to 290 C., in order to bodythe product. In our practice, we consider that the final step iscompleted when samples thinned with an equal weight of mineral spiritshave a viscosity between E and G on the Gardner- Holdt scale. This finalbodying step may take about 2 hours but as pointed out, the bodying andesterification may be carried out simultaneously.

We have also found that the steps of neutralization and esteriflcationcan be avoided by using a polyhalogenated polyhydric alcohol which willreact directly with the fatty acid soaps. For example, if a mixturecontaining approximately 2 mols of fatty acil soap for each mol of anatural resin is treated with dichlorohydrin. a reaction will take placewith the precipitation of the alkali salt, and the resin acids can beesterified with the residual hydroxyl groups of the dichlorohydrin.Where larger amounts of resin are present, mixtures of monochlorohydrinand dichlorohydrin can be employed. On the other hand, where a varnishis being prepared of a relatively high oil length, a small amount of thesoap may be neutralized, as for example with a bisulphate ormonophosphate or even with small quantities of an acid such as sulphuricor hydrochloric acid. In such case the released fatty acids can reactwith the hydroxyls of the halogenated polyhydric alcohol or with otherpolyhydric alcohol which may be added. Obviously in addition to thehalogenated glycerides, other halogenated polyhydric alcohols may beemployed.

This process is particularly useful with any oil which containsappreciable amount of fatty acid groups having at least two double bondsin the isolated position, that is, non-conjugatedI Such oil may include,for example, linseed oil, fish oil. soybean oil, perilla oil or theirequivalents. The process may also be employed with oils having some orall of their double bonds in conjugated positions as for example withdehydrated castor oil. In such case the benefits of our process are notalways so apparent.

Our process can readily be understood from the following illustrativeexamples which show some preferred forms of carrying out the same:

Example I 500 parts of WG rosin was melted and heated at a temperatureof between 200 C. and 240 C. in an open kettle. 5085 parts of a linseedsoap solution equivalent to 1000 parts of linseed oil was added slowlyover a period of 2 hours while the mixture was stirred gently. The rateof soap addition was determined by the rate of foaming. After the soapsolution was added. the rosin soap mixture was heated at 260 C. for 3hours. rosin fatty acid mixture was recovered by treating the rosin soapmixture with a slight excess of 45% sulphuric acid. The freed acids werethoroughly Washed with water and dried. The final acid value was 169.

300 parts of these acids was mxed with 29 parts of glycerol and themixture was heated for 3 hours at a temperature of between 180 C. and200 C. The temperature was then raised to 260 C. and held for 12 hourswhile carbon dioxide was passed through the mixture. At the end of thattime the mixture was thinned with mineral spirits to yield a varnishcontaining 55% solids and was treated with .75% Pb and 06% Co as driers.The varnish had a viscosity of D on the Gardner-Holdt scale and an acidvalue of 6.

Example II 600 parts of linseed fatty acids was heated to about C. and117 parts of sodium methoxide was gradually added. The resulting soapymass was heated to about -120 C. and cooled. 300 parts of 99% abieticacid was melted at a temperature of between 110 and and the spongy soapwas added. The mixture was then gradually heated with stirring to atemperature of 240 C. and held for 5 hours. The soap was decomposed with45% sulphuric acid and the final acid value was 186.

'790 parts of these acids was mixed with 84 parts of glycerol and thismixture was heated with stirring for 6 hours at a temperature of between230 and 240 C. with passage of carbon dioxide. The resulting productshowed a viscosity of Z-6 on the Gardner-Holdt scale and an acid valueof 7.5. For the purpose of comparison 600 parts of linseed fatty acidswas heated with 300 parts of 99% abietic acid and esteriiied withglycerol. The resulting product had a viscosity of M on theGardner-Holdt scale and an acid value of 11.5.

Example III 250 parts of run East India resin was heated to atemperature of between 200 and 240 C. in an open kettle and linseed soappaste equivalent to 500 parts of linseed oil was gradually added and theresulting mixture was heated to 260 C. for 3 hours. After neutralizationwith sulphuric acid and thorough washing the final acid value of themixture was 139. In order to prepare a 25- gallon varnish from theseacids they were acidified with 20 parts of glycerol. The resultingsolids were thinned with mineral spirits to 50%. solids and driers addedas before. The final varnish had a viscosity of L on the Gardner-Holdtscale and an acid value of 4.7.

Example IV 400 parts of rosin was melted as in Example I and as beforewas treated with linseed soap paste equivalent to 400 parts of linseedoil. After following out the procedure outlined in Example I through thepoint of neutralization, the mixture showed an acid value of 145. 275parts of these acids was esterified with 23 parts of glycerol to producea 12 /2 gallon varnish. After esterification was completed the mass wasthinned with mineral spirits to 50% solids and treated with The.

driers as before. The resulting varnish showed a viscosity of between Eand F on the Gardner- Holdt scale and an acid value of 1.8.

It is understood that these examples are given only by way ofillustration and that the same may be modified in many particularswithout departing from the spirit of our invention.

What we claim is:

1. In the process of making varnishes the steps which comprise heatingtogether for at least about two hours soaps of drying oil fatty acidshaving non-conjugated double bonds and an oil soluble varnish resin inproportions to give a varnish length of between 5 and 30 gallons and ata temperature of between 200 C. and 285 C., and subsequently forming apolyhydric alcohol ester of the fatty acids represented in the soap, inthe presence ofsuch resin.

2. A process as specified in claim 1 in which the resin isa naturalvarnish resin and the fatty acids are liberated with acid andsubsequently the fatty acids and natural resin acids are esterifled witha a polyhydric alcohol.

3. A process as specified in claim 1 in which the polyhydric alcohol ishalogenated and the halogenated alcohol is caused to react directly withthe soaps.

4. A process as specified in claim 1 in which the temperature is inexcess of 240 C.

5. In the process of making varnishes, the steps which comprise addingwater wet soap of drying oil fatty acids having non-conjugated doublebonds to melted natural varnish resin, heating the resulting mixture toa temperature of between 200 C. and 285 C. for from 2 to 10 hours,adding acid to release the fatty acids, washing and esterifying thefatty acids and resin acids with a polyhydric alcohol.

6. A process as specified in claim 5 in which the temperature is between240 C. and 260 C.

7. In the process of making varnishes from varnish resins and dryingoils having non-conjugated bonds, the steps of forming a soap of thefatty acids of such drying oil and heatingsuch soap with an oil-solublevarnish resin for at least two hours at a temperature of between 200 C.and 285 C., the resin being present in proportion to give a varnishlength of between 5 and 30 gallons. 7 r

ALFRED E. RHEINECK. SAMUEL B. CRECELIUS.

